Crystallization and preliminary X-ray studies of annexin IV (endonexin), a calcium-dependent phospholipid-binding protein.

Annexin IV (endonexin) has been purified from chicken liver and crystallized by the vapour diffusion method. Crystals which diffract to at least 2.2 A have been obtained. They belong to space group R3 and have unit cell dimensions of a = b = 99.4 A, c = 96.2 A, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees. There is one molecule of 32,500 Da per asymmetric unit.     

Characteristics of murine monoclonal anti-CD4. Epitope recognition, idiotype expression, and variable region gene sequence.

We have characterized a series of mouse monoclonal anti-CD4 and describe both their CD4 epitope recognition and Id expression. We also determined the V region gene sequences of these antibodies in an attempt to correlate epitope recognition and Id expression with V region sequence. All of these preparations recognize epitopes that cluster around the HIV gp120 binding site on the human CD4 molecule. However, we observed differences in epitope recognition among the anti-CD4 preparations, based on either competitive inhibition assays or functional assays, such as syncytium inhibition. Analysis of Id specificities using a polyclonal anti-Id generated against anti-Leu 3a indicated that five of the seven monoclonal anti-CD4 expressed a shared Id. Based on V region gene sequences, the V region kappa-chain (V[kappa]) from each of the seven antibodies was encoded by the V[kappa]21 gene family and expressed the J[kappa]4 gene segment. Those preparations that expressed the shared Id with anti-Leu 3a have virtually identical V[kappa] sequences, with a high degree of homology in the CDR. The VH region gene sequences of six of the seven antibodies also shared overall homology and appeared to be encoded by the J558 VH gene family. The seventh anti-CD4 VH region is encoded for by the VHGAM gene family. The majority of these antibodies used JH3 gene segment, although the JH2 and JH4 gene segments were also represented. In addition, several of these antibodies share a common sequence organization within their V-D-J joining regions that appears to involve N and P sequences to generate unique D segments. Together, these data suggest that differences in epitope recognition among the monoclonal anti-CD4 may reflect sequence variability primarily within the CDR3 region of both V[kappa] and VH. The basis for the detection of a shared Id most likely reflects the high degree of homology within the V[kappa] region sequences. In addition, these data, which are based on a limited analysis, suggest the possible restricted use of V region germ-line gene families in the secondary antibody response of BALB/c mice to specific epitopes on the human CD4 molecule.     

Estrogen induced changes in uterine sensitivity for the decidual cell reaction: Interactions between prostaglandin E2 and histamine or bradykinin

In rats receiving high doses of estrogen along with progesterone, the uterus is desensitized and does not respond to artificial stimuli with increased endometrial vascular permeability or decidualization. In addition, prostaglandin E₂ (PGE₂), the putative mediator of endometrial vascular permeability changes in sensitized uteri, is ineffective when given into the uterine lumen. The possibility that this inability of PGE₂ to increase endometrial vascular permeability may be related to the unavailability of hitamine of bradykinin was investigated. Rats were differentially sensitized for the decidual cell reaction by the daily injection of 2 mg progesterone with either 0.5 of 10 μg estrone for the 3 days preceding the unilateral intra-uterine injection of 50 μl phosphate buffered saline containing gelatin with or without 10 μg PGE₂ and with or without 1 mg histamine or 1 μg bradykinin. Prior to the intrauterine injection, all rats were treated with indomethacin to inhibit endogenous prostaglandin production. Endometrial vascular permeability changes were determined 8 h later by determining radioactivity levels in injected and non-injected uterine horns 15 min after the i.v. injection of ¹²⁵I-labelled bovine serum albumin. PGE₂ increased endometrial vascular permeability in rats receiving 0.5 μg estrone, but not in those receiving 10 μg. Histamine or bradykinin, alone or with PGE₂, did not affect endometrial vascular permeability in rats receiving either estrogen dose. The data suggest that the unresponsiveness of uteri from rats treated with high doses of estrogen is not simply due to the unavailability of bradykinin or histamine.     

Structural data for the carbohydrate of ispaghula husk ex Plantago ovata forsk

The husk from the seeds of Plantago ovata Forsk yielded two fractions when exposed to mild aikali, namely, the mucilage polysaccharide (85%, apparently a single species) and the non-polysaccharide component (15%). Methylation analysis and partial hydrolysis with acid showed the mucilage polysaccharide to be a highly branched, acidic arabinoxylan, the xylan backbone having both (1→4) and (1→3) linkages. The majority of the residues in the xylan backbone are variously substituted at O-2 and O-3 with arabinose, xylose, and an aldobiouronic acid identified as 2-O-(galactopyranosyluronic acid)-rhamnose. A structure incorporating these features for the husk polysaccharide is proposed.     

Influence of nutrition on reproduction in the ewe with special emphasis on progesterone concentration.

Influence of nutrition on lambing rate and progesterone levels was studied in Rambouillet ewes. In the first experiment, two groups of 10 ewes each were individually fed on a diet containing either high (3.04 kg/day) or low (1.89 kg/day) levels of total digestible nutrients. Ewes on the High Plane of nutrition had lower pregnancy rates and fewer lambs than the ewes on the Low Plane. Plasma progesterone concentration was not significantly different between treatment groups when compared before and after mating.In the second experiment two groups of 25 ewes each were grazed on pasture and supplemented with a pelleted concentrate. One group was fed to gain weight, while the other group was fed to maintain their body weight. There was no significant difference in lambing rate between these two groups.     

Mutant p53: it’s not all one and the same

Mutation of the TP53 tumor suppressor gene is the most common genetic alteration in cancer, and almost 1000 alleles have been identified in human tumors. While virtually all TP53 mutations are thought to compromise wild type p53 activity, the prevalence and recurrence of missense TP53 alleles has motivated countless research studies aimed at understanding the function of the resulting mutant p53 protein. The data from these studies support three distinct, but perhaps not necessarily mutually exclusive, mechanisms for how different p53 mutants impact cancer: first, they lose the ability to execute wild type p53 functions to varying degrees; second, they act as a dominant negative (DN) inhibitor of wild type p53 tumor-suppressive programs; and third, they may gain oncogenic functions that go beyond mere p53 inactivation. Of these possibilities, the gain of function (GOF) hypothesis is the most controversial, in part due to the dizzying array of biological functions that have been attributed to different mutant p53 proteins. Herein we discuss the current state of understanding of TP53 allele variation in cancer and recent reports that both support and challenge the p53 GOF model. In these studies and others, researchers are turning to more systematic approaches to profile TP53 mutations, which may ultimately determine once and for all how different TP53 mutations act as cancer drivers and whether tumors harboring distinct mutations are phenotypically unique. From a clinical perspective, such information could lead to new therapeutic approaches targeting the effects of different TP53 alleles and/or better sub-stratification of patients harboring TP53 mutant cancers.Subject terms: Cancer genetics, Tumour-suppressor proteins